That's a ridiculous statement. There are so many other skills that could save your life one day, not knowing how to do that particular one isn't any stupider than not knowing how to climb a tree to escape a bear.
I agree people should be given the opportunity to learn how to swim but let's look at reality for a moment: Worldwide, almost 60% of humans do not know how to swim and they still get by fine... Wild, isn't it?
Because you're never going to leave your home. So, yes, you don't need to be an Olympic athlete but if you can't basically swim you're stupid.